1. Field of the Invention
The present invention relates to a hybrid gas-insulated switchgear in which a single-line diagram unit is constructed by arranging and connecting in series modules each formed by housing a circuit breaker, disconnecting switches, grounding switches (earthing switches), etc., together inside a single tank segregated into gas compartments.
2. Description of the Related Art
A 1½ circuit breaker system gas-insulated switchgear constituting a switchgear portion of a transformer facility in which electric power transmission lines and buses are constituted by overhead lines is described in Japanese Patent Laid-Open No. HEI 11-69532 (Gazette), for example.
FIGS. 13A and 13B are diagrams explaining a construction of a conventional 1½ circuit breaker system (hereinafter “CB system”) gas-insulated switchgear such as that described in Japanese Patent Laid-Open No. HEI 11-69532 (Gazette), for example, FIG. 13A showing a plan thereof and FIG. 13B showing a front elevation thereof.
In FIGS. 13A and 13B, three circuit breakers 1 are disposed in a straight line, current transformers 10 are connected to first and second ends of each of the circuit breakers 1, and a disconnecting switch 9 and a grounding switch 8 for inspection are connected to each of the current transformers 10. Line bushing cases 11 are each disposed between the disconnecting switches 9, line bushings 2 for connection to electric power transmission lines or circuits of transformers, etc., being mounted to each of the line bushing cases 11. Bus bushing cases 12 are each disposed outside the disconnecting switches 9 at first and second ends of the apparatus, bus bushings 3 for connection to main buses being mounted to each of the bus bushing cases 12. Line grounding switches 6 are connected between the line bushings 2 and the disconnecting switches 9, lightning arresters 4 and lightning arrester disconnecting switches 5 are connected to the line bushings 2, and bus grounding switches 7 are connected near the bus bushing 3. Finally, connection buses 13 are each added between one of the line bushing cases 11 and one of the circuit breakers 1, gas-insulated voltage transformers 14 being disposed below the connection buses 13.
Thus, in a conventional gas-insulated switchgear, an electrical circuit for a single-line diagram unit is constructed by combining items of electrical equipment such as the circuit breakers 1, the disconnecting switches 9, the grounding switches 6, 7, and 8, etc. The items of electrical equipment such as the circuit breakers 1, the disconnecting switches 9, the grounding switches 6, 7, and 8, etc., are each disposed inside a separate tank, electrical insulation space being disposed between each of the tanks.
Because a conventional gas-insulated switchgear is constructed in the above manner, one problem has been that tanks for housing the electrical equipment are enormous size and electrically-insulating spacers are disposed between each of the tanks, preventing reductions in size and cost.
Furthermore, when an electrical facility such as a transformer substation or a generating station, etc., is being freshly installed or added to, because the tanks in which the circuit breakers 1, the disconnecting switches 9, the grounding switches, etc., are each housed must be carried to the site, and the tanks must be arranged and connected on site so as to provide adequate distance between each of the items of electrical equipment, and the line and bus bushings must also be mounted, other problems have been that the installation footprint is large, the installation workload is increased, and installation time is prolonged.